what are the advantages and disadvantages of eco towns?

Advantages:
-Models of sustainability to carry us forward into the future
-Practical application of smart growth ideas to see what will work the best. It's like a trial run, that if successful, can become the real thing.

Disadvantages:
-They're generally being built on greenfield (ie. undeveloped, natural) land, which works against smart growth principles. Smart Growth hinges on infill and re-development, rather than paving over more greenfield.
-Cost. It's expensive to build sustainable communities, and for people to buy homes in them as a result.